The impulse initiation of arc discharges

An analysis is made of discharge characteristics when arc initiationis just possible, and effects due to electrode material, shape and surface condition are studied. After the energy associated with the initial high-voltage pulse has dissipated, the current is shown to be of the order of 0.1 amp. The discbarge is then unstable, and frequent transitions may occur between glow and arc conditions. Agreement hasbeen obtained with discharge characteristics obtained under steadystate conditions. Criteria for arc initiation have been derived in terms of the discharge characteristics. These results axe significant for an understanding of the developmentof a power arc in the path of a surge breakdown on electrical apparatus especially for gaps up to about 1 cm.